Fred,My english is too poor...but, I will try... 
The questiion is, in my opinion a cheaper Line Array is better than
the simple speaker. I finished a LA with equivalent US$ 300,00 (see at
http://www.mrweb.com.br/fvm/laf2/) and this have a sound much bether
than a B&W DM series for example (US$ 800,00 in Brazil).
I will try make a Ribbon tweeter because in Brazil, do not have Ribbon
for sale and the cost for import is very high.
[]'s
Renato